docs: def _validate(self):
          """ check if this Swagger API valid or not.
  
          :param bool strict: when in strict mode, exception would be raised if not valid.
          :return: validation errors
          :rtype: list of tuple(where, type, msg).
          """
  
          v_mod = utils.import_string('.'.join([
              'pyswagger',
              'scanner',
              'v' + self.version.replace('.', '_'),
              'validate'
          ]))
  
          if not v_mod:
              # there is no validation module
              # for this version of spec
              return []
  
          s = Scanner(self)
          v = v_mod.Validate()
  
          s.scan(route=[v], root=self.__raw)
          return v.errs